From a typical place Earth, how many feet or miles must you go to be considered in outer space?

"There is no firm boundary where outer space starts. However the Kármán line, at an altitude of 100 km (62 mi) above sea level, is conventionally used as the start of outer space in space treaties and for aerospace records keeping."--Wikipedia

An astronaut is 72 miles in space

that depends how 'high' you are...

So basically, if you are flying an international commercial flight at an altitude of 38000 feet, you are just about where outer space begins?

5 miles.